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Wednesday, July 3, 2019

Structure of phosphorous trioxide (P4O6) and phosphorous pentaoxide (P4O10) :

Phosphorous is a pentavalent element hence show +3 and +5 oxidation state (d orbital presence).it form two oxide P2O3 (+3) and P2O5 (+5). These oxide of phosphorus exist as dimer in form of P4O6 (+3) and P4O5

Comparative Study of P4O6 and P4O10 :

SN
Properties
P4O6
P4O10
1
Hybridisation (P) atom
 Sp3
Sp3
2
Hybridisation (O) atom
Sp3
Sp3 /Sp2 of Vertex (O)
3
No of Bridge bond (P-O-P)
6
6
4
No of Six member ring
4
4
5
No of Total  (l.p.)
16
20
6
No of Back Bond
0
4
7
No of P(pi)-P(pi) Bond
0
0
8
No of 2P(pi)-3d(pi) Bond
0
4
9
Longer (P-O) Bond
All are equal
12
10
Shorter (P-O) Bond
All are equal
4
11
Bond Length (P-O)
166 pm (Longer)
145 pm (shorter)
12
Bond Angle (O-P-O)
99.5 =100 (smaller)
102 (bigger)
13
Bond Angle (P-O-P)
127 (bigger)
123 (smaller)
14
No of Sigma Bond
12
16
15
No of (Pi) Bond
0
4
16
No of oxygen atom attached with( P)
3

4

Common feature of P4O6 and P4O10 :

(1) Both oxides have closed cage like structure.
(2) Both oxides contain six (P-O-P) Bond.
(3) Both oxide have 4 six member ring.
(4) Both are the anhydride of their respective acids.
(5) Both are Non planer

Explanation of Different Bond length and Bond Angle In P4O6 and P4O10 :
(1) According to "Bent's rule" lone pair electron  prefer to Stay to in those atomic hybrid orbitals have more % s-character.
(2) In case of P4O6 molecules, atomic hybrid orbitals containing lone pair electrons have more (s) character and less (p) character hence shorter bond length while remaining orbitals have less (S) character and more (p) character hence longer bond length (X1) than (X2) in P4O10 .
(3) We know that On increasing % s character in hybrid orbital, the bond length decreases while bond angle increases.
(3) In Case of P4O (O-P-O) bond angle is smaller due to higher p-character in atomic hybrid orbitals than orbital containing (O-P-O) in P4O10. (have more s-character )
For reading more Details about  click on  Bent Rule and Drago’s rule 

Related Questions:



Trisilyl amine, N(SiH3)3 is planar whereas trimethyl amines N(CH3)3 is pyramidal. Explain why?.















NITROGEN : AND ITS PROPERTIES:


Nitrogen (N) and its Behaviour:
(1) Nitrogen is the lightest element of 15th group with the symbol N and atomic number 7. It often called the pnictogens. The name pnictogens comes from the Greek πνίγειν "to choke", directly referencing nitrogen's asphyxiating properties.
(2) The name Nitrogen gets its name from a mineral known as “niter” (potassium nitrate), from which it can be prepared. It was first discovered and isolated by a Scottish physician Daniel Rutherford in 1770.
(3) Nitrogen is a fairly common element in the earth’s crust. It is most important constituent of atmosphere, making up to 78.08 %. Nitrogen is a colorless, odorless, non combustible and nontoxic gas. Makes up the major portion of the atmosphere, but will not support life by itself.
(4) The greatest use of nitrogen is in ammonia which is used for fertilizer production and to produce nitric acid. Nitrogen gas is used where inert atmosphere is needed, such as in an ordinary light bulb. Nitrogen is also used in protecting historic documents. Nitrogen is also used in storage of food stuff and in explosives.
(5) Nitrogen is use in purging air conditioning and refrigeration systems, and in pressurizing aircraft tires. It May cause asphyxiation by displacement of air. Under prolonged exposure to fire or heat containers may rupture violently and rocket
(6) Nitrogen is absolutely essential to all living organisms. It is important part of all protein molecules which, among other functions, are the building materials in all kinds of cells.

Abnormal Behaviour of Nitrogen:

(1) Nitrogen is a gas, while other elements are solids.
(2) Nitrogen molecule is diatomic (N2) while molecules of P, As and Sb are tetra atomic (P4, As4, Sb4) and that of Bi is mono atomic.
(3) Halides of nitrogen except NF3 are highly explosive.
(4) N2O3 and N2O5 are monomeric while trioxides and pentoxides of P,As and Sb are dimeric.
(5) It is chemically inert due to the presence of triple bond other elements are highly reactive due to presence of single bond in their molecule.
(6) N2, CO, (CN)¯ are isoelectronic species but N2 is less reactive due to nonpolar nature and high ionisation energy.
(7) N does not form sulphides.

Related Questions:



Trisilyl amine, N(SiH3)3 is planar whereas trimethyl amines N(CH3)3 is pyramidal. Explain why?.















Tuesday, July 2, 2019

Oxy acids of Phosphorous:


Phosphorus forms two series of oxyacids namely; phosphorus acid and phosphoric acid.
SN
Element
Formula
Name of the Oxyacid
O.S.
2
Phosphorus
H3PO2
H3PO3
H4P2O7
Hypo Phosphorus acid
Ortho Phosphorus acid
Pyro phosphorous acid
+1
+3
+3
3
Phosphoric
H4P2O6
H3PO4
 H4P2O7
(HPO4)n
Hypo Phosphoric acid
Ortho Phosphoric acid
Pyro Phosphoric acid
Meta phosphoric acid
+4
+5
+5
+5
4
Arsenic
H3AsO3
H3AsO4
Arsenious acid
Arsenic acid
+3
+5
5
Sb & Bi
No stable acid



 (A) Phosphorus acid series: (Structure)
The series consists of p atom exhibiting oxidation state of +3. They act as reducing agents.
                

(B) Phosphoric acid series: (Structure) 
This series consist of acids having p in +5 oxidation state.
   
                           
Note : Meta phosphoric does not exist in monomeric form, but it exists as cyclo meta phosphoric acid (HPO3)3 or   polymeta phosphoric acid (HPO3)n.  Sodiumhexametaphosphate is a famous salt known as CALGON  and use water softener.


Special Note:
(1)  Meta is used for acid obtained by loss of H2O molecule.
(2)  Pyro is used for the acid obtained from two molecules with a loss of H2O.
(3)  Hypo is used for the acid having lower oxygen content than the parent acid.

Related Questions:



Trisilyl amine, N(SiH3)3 is planar whereas trimethyl amines N(CH3)3 is pyramidal. Explain why?.